In this scene the shaft's ladder breaks and sends Daniel tumbling to the bottom, breaking his leg in the process. When he hits the bottom he inspects his leg but eventually ignores it to check the rock he just blasted with dynamite to see if it contained any silver. With his silver in his pocket he drags his injured body out of the hole and slides back to his camp presumably to show everyone proof that the mine shaft is a silver deposit. This all symbolizes that Daniel will put anything on the line to get his job done, and the job is the object of utmost importance to his character.
This is also the first of many occasions where the failure of machinery leads to the injury or death of someone in the film.
